The following is a tabulation of some U.S Patents and U.S. Patent Application Publications that presently appear relevant:
U. S. PatentsPatent NumberKind CodeIssue DatePatentee2,499,791B11950 Mar. 9Spencer4,412,601B11983 Nov. 1Cooper5,203,619B11993 Apr. 20Welsch et al5,475,949B11995 Dec. 19McCoy5,535,852B11996 Jan. 16Bishop et al.5,667,035B11997 Sep. 16Hughes6,131,702B12000 Aug. 17Berridge6,250,728B12001 Jun. 26Thorp6,779,634B12004 Aug. 24Slagle7,575,098B22009 Aug. 18Hartley7,963,505B22011 Jun. 21Taylor et al.8,418,814B12013 Apr. 16ByersU. S. Patent Application PublicationsPublication NrKind CodePubl. DateApp or Patentee2003/0192836A12003 Oct. 16Ulrich2006/0066188A12006 Mar. 30Crawford2008/0296089A12008 Dec. 4Penn et al.
A typical method of roof construction in residential and office structures include manufactured wood or cold formed steel trusses or similar types of construction. The terms “truss or trusses” are used herein to include similar types of framing methods which are common in residential structures. Trusses are typically installed with a uniform spacing. A common spacing is 24 inches in the US system or 600 mm in the SI system. Typical installation of trusses results in open space between each truss, over the height of the truss and along its length (i.e., attic space). This attic space is typically accessed through a small access hatch located in a closet, hallway or garage. Such access is generally for maintenance and is not intended for storage access.
In some cases there is also a formal attic framed inside the roof structure, particularly over garages. The attic space may be framed inside the truss, or may be framed using separate ceiling joists. However, even in these cases the access is generally through a small opening, such as, for example, with a drop down ladder. Further, older structures are typically constructed with site built framing including rafters, ceiling joists and strong backs and kickers to support the roof. The attic space created is similar to that for trusses.
Systems relative to access of attic space have generally been along two separate, but related, avenues. The first is represented by a platform lift to move items from a garage floor to and from attic storage above and the second is represented by a closet that is lifted up into the attic space. In some examples, these systems are designed for long term storage. However, there is also a need to lift items from one level to a level above for everyday use. Systems similar to that of a dumb waiter may be less than ideal for everyday use. A dumb waiter typically has at least one permanent rail over the length of the lift and typically is inside an enclosed shaft, thereby taking up floor space.
Examples of platform lift systems to move items for storage from a lower level (e.g., a garage) to a level above (e.g., an attic) are described in Bishop, Hughes, Berridge, Penn et al., Hartley, Taylor and Byers. These systems are utilitarian in nature and are not suitable for use in livable or office space. These systems are composed of a platform supported by cables that are attached to a motorized pulley system. The pulley system is generally supported on the floor/ceiling structure of the upper level. These cable supported platforms do not, by their nature, have lateral or torsional stability in the horizontal plane other than that provided by the restoring force due to the displaced angle of the cables. This can lead to the platform moving like a pendulum and twisting about a vertical axis. This movement poses problems when used in livable or office space and could result in damage to items around the shelf as well as contents of the shelf, and poses a hazard for persons near the shelf. A further disadvantage is that care must be taken to ensure the shelf is stable when being raised or lowered and is lined up with the hole in the ceiling into which the platform must enter.
Bishop et al and Hughes use sets of telescoping tubes, typically three sections in length, with the lifting cables inside the tubes. For the sets of telescoping tubes in Bishop et al and Hughes, because the lower tubes pass inside the upper tubes, there can be no attachments, such as shelves, along their length. Further, the ability to increase the height of the lift above the ceiling level is restricted because it increases the free length of the telescoping tubes, making them even more flexible. Although the tubes can provide some stability compared to other cable systems, due to their unsupported length when in the lowered position, and the method of attachment to the structure above, the amount of lateral stability provided is questionable. The indicated connections to the structure are not adequate to reliably fix the tubes and could significantly degrade with use. In addition, the weight of the platform is carried by the cables inside the tubes, thus the tubes do not benefit from increased stiffness which would result from tension in the tubes.
In addition to the disadvantages described above, platform lifts generally suffer from at least one or more of the following disadvantages: (a) Utilitarian in design, limited attempt to address aesthetics for use in livable or office space; (b) Questionable lateral stability, which is important for storage of some items and may be a safety and operational concern in occupied areas; (c) Only receives support from the upper floor or ceiling structure. In the case of trusses, a platform is only supported on the bottom chord; (d) Generally require more room to install than is available between trusses; (e) Intended to be in the raised position when not in use. These lifts are not intended to be used as shelves in the lowered position; (f) Support only a single platform; (g) Presume that the floor or ceiling framing is adequate to support the anticipated loading. Although in some cases supporting structures can be addressed during installation, there are no provisions accounted for in the systems to aid in this regard.
Examples of closet systems including shelving or cabinets that are lifted up into an attic space are described in Spencer, Cooper, Welsh et al., McCoy, Thorp, Ulrich, Crawford. Generally, these cabinets are intended for relatively light loads such as storing clothes.
Spencer shows a cabinet, called a disappearing closet, which can be accessed when in its lowered position and is hoisted up into an enclosed attic space when not in use. Although the box is lifted with cables, there are guides on the sides as well. The guides do not appear to provide much stability, but are used to guide the closet into the upper compartment. The guides are separate from the cables and are visible when in the lowered position. The cabinet does not provide for a ceiling closure when either in the lowered or raised position. The space in the attic which houses the closet in the raised position can isolate the contents form the rest of the attic space, but it is noted that in Spencer the motor is outside the box and drive chains penetrate the box, resulting in a problem with sealing the enclosure from the unconditioned attic space. Further, no mechanism is provided to lower the closet in the event of a power or equipment failure. Therefore, repairs generally would need to be made from inside the attic. This could require partial deconstruction of the upper compartment for access.
Welsh et al. shows a vertically retractable shelf which addresses the stability in the horizontal plane in a positive manner. However, the shelf in Welsh et al. does not telescope down from the ceiling. This system may only be suited to situations wherein there is a drop ceiling below a floor or ceiling structure.
McCoy shows a design for a telescoping ceiling closet. The telescoping, however, is the closet itself, so the top of the shelf cannot be lower than the ceiling. This means that to drop the bottom of the shelf to within a reasonable distance of the lower floor, the shelf must be tall, which in turn requires a tall attic space. The indicated construction and the lifting mechanisms (i.e., springs or motorized with rack-and-pinion gear on one side) indicate the system is intended for light storage, consistent with a small and light closet. Thorp and Ulrich show storage systems with similar limitations.
Crawford shows a design for a retractable shelving system which includes an enclosure into which the shelves retract. The retractable shelving appears to be stable and positively guided up into the enclosure. The system does not telescope and the top of the shelf is at the ceiling. Therefore the height of the shelving is limited, to a much greater extent than the telescoping systems, to the available height in the attic. It is touted that the shelf can be constructed from within the hole created by the cabinet space. It is noted that some access is probably required to modify framing if moderate loads are required, to run electrical, possibly repair insulation and address other systems that typically exist in an attic.
Closet lift type systems generally suffer from at least the following disadvantages: (a) Utilitarian in design; (b) When in the lowered position, do not provide a ceiling closure; (c) When in the lowered position, the cables and guides are visible and unsightly; (d) Closets that extend to the ceiling when in the lowered position, require a tall closet and therefore a tall attic space in order to be accessible near floor or table height; (e) Maintenance of the lifting mechanism (motor, pulleys, springs, guides, etc.) will typically require access from the attic and partial removal of the housing in the attic; (f) As depicted in the patents, the closet systems address relatively light loads. Methods for increasing the capacity of the supporting framing are not addressed; (g) In addition, many of the disadvantages given for platform lifts apply.
None of the above devices and patents, taken either singly or in combination, is seen to describe the instant invention.